The present invention relates to semiconductor lasers, and more particularly, to a ruggedized, tunable, athermal laser diode source assembly.
The advent of lasers as a source of coherent light has enabled design of highly accurate devices for timing, measuring, switching, and various other functions of optical information transmission and processing. Of particular note is the high degree of efficiency achievable with laser diodes, even when operated at high switching rates.
A laser diode source assembly can be thought of as a sophisticated housing for a simple diode laser. It collimates the rapidly diverging beam from the laser, Preferably with minimal loss in laser power. A typical source assembly might include a collimating lens supported in fixed relation to a diode laser source. The diode in turn is typically driven by a local electronics package. Where all of these elements are combined together in a single assembly, however, any heat generated within this assembly, or even external thermal gradients, can cause physical device changes as will degrade component performance, or as can defocus the assembly.
It is known to provide thermal compensation to aid in maintaining the frequency of operation of a laser. In a gross attempt, cooling chambers can be employed within which a source assembly can be operated with diminished thermal anomalies. However, this can prove to be cumbersome and expensive, at least from the standpoint of supporting equipment.
As well, a laser diode source assembly is limited in value if it cannot tolerate real world insults. These insults include those imposed during transportation, installation and use. A source assembly must be particularly hearty if it will be subjected to airborne distresses, such as high gravity forces and vibrations of rocket lift-off, etc.
In fact, there is a felt need and a ready market for an athermal, ruggedized, frequency tunable laser source with good power output (on the order of 25 mW at a 0.86 micron wavelength) with a high degree of frequency stability.